" Let me hypothesize a political scenario on the 50th anniversary of Apollo 11’ s landing on the moon, in 2019. The U.S. President, whoever that may be, takes the opportunity to direct the future of human space exploration, pioneered by Americans, by stating in a speech: “I believe that this nation should commit itself, within two decades, to establish permanence on the planet Mars. "

― Buzz Aldrin , Mission to Mars: My Vision for Space Exploration